Apron drier



April 11, 1944. y F B, MQRRILL 2,346,138

APRoN DRIER Filed March 27, 1941 5.Sheets-Sheet 3 ALD 'm i 1 /gvevd-;

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Patented Apr. 11, 1944 APRON DRIER Frank B. Morrill, North Adams, Mass., assignor to The James Hunter Machine Company, North Adams, Mass., a corporation of Massachusetts Application March 27, 1941, Serial No. 385,399

3 Claims. (01.344223) This invention relates to loose stock driers of the type in which woolen, rayon, and other fibers are deposited, after dyeing or other processing, in a layer upon an air-pervious apron which travels through a housing while currents of heated air are directed against and through the apron and the stock carried thereby, to dry the stock.

Since the fibers are wetand cling together in clumps or wads as deliveredl onto the apron by the hopper-feeder conventionally used to spread the material out over the apron, the drying air when caused to ow through the apron and the layer of stock thereon bya difference in atmospheric pressure at the two surfaces of the apron tends naturally to take the paths of least resistance and pass between the wads of stock so far as possible, ratherV than goingthrough the' wads, thus drying the bers at the interior of the wads more slowly than those outside, resulting in un-A even moisture content of the dried stock when it reaches subsequent stages in processing.

Toremedy this, it is common to resort to the use of a relatively thick layer of stock on the apron, so that the upper clumps will close the apertures between the under'ones, thus forcing more of the air to pass through the clumps. However, this practice cuts down the rate of production of the drier because the thick sheet dries more slowly, or else requires the expenditure ofAv considerably more power in the blowers in order to build up an air pressure suflicient to penetrate and flow through the stockcopiously, in either event tending to dry the topportion beyond the optimum desired moisture content. Also,4 When it is employed this resort to higher pressure introduces accompanying drawbacks, through blowing the stock off laterally from the apron to jam in the chains carrying the apron and in its guards and to clog the heaters, and through blowing it off endwise also; the unavoidable airleaks in the housing waste more heat as the amount of escaping hot air increases with the pressure.

Recognizing that air Vtraveling at high velocity can be made to penetrate more deeply into wadded libers by reason of its momentum than air merely flowing over the surface thereof and free to turn aside to follow .an easier path, som'e effort has been made to profit therefrom by directing high-speed jets of air against athinvlayer of wet stock laid out on the pervious traveling apron. But so far as I am aware this has a1- ways been done heretofore by the method Lof creating a static pressure byblowers and then converting a part of this into kinetic pressure by the use of nozzles or baies creating a constricted path for the air-'blastv in order to raise the velocity of the air so that its momentum would cause the desired penetration of the fibers. Not only does the cost of the nozzles and the small area of the apron served by each nozzle add to the cost of the drier and slow down its production, but the kinetic energy imparted to the air by the blowers is thrown away in converting the total energy into static pressure and then reconverting part of it into kinetic energy at the nozzles by, constricting the path of flow.

Hence, a main object of my invention is to attain more uniform drying and a greater rate of production by drying a thin layer of loose stock under the impact of streams of air having both static pressurel and kinetic energy and penetrating the stock at relatively high Velocity, without the expenditure of the excessive amounts of power heretofore needed to drive the blowers when producing the requisite highspeed jets by the roundabout method described, orfwhen merely creatingl a` high static pressure. In accordance with the invention, this is accomplished by mounting centrifugal blowers directly over the apron to discharge their blasts straight at the layer of stock at short range and at right angles thereto, preferably locating a plurality of centrifugal blowers side by side across the width of the apron at successive points in the length thereof and With the blowers of one such transverse row staggered with respect to the blowers of the adjacent row to as'sure complete coverage of the entire width of the layer by blasts of practically equal intensity.

Since the kinetic energy of lthe blowers blasts is not lost through use of distributing devices such as nozzles or baliies deflecting the blasts, forwardly-curved blades are used in the centrifugal blowers, producing a larger volume of discharged air from the same sizes of blowers with less power consumption than where static pressure alone is useful and wanted. In prior types of apron driers, where the kinetic energy of the air is wasted, the blowers utilize radial or ba-ckward1ycurved blades to throw the air off radially against the blower-housing interior and thus build up preponderantly static pressure, because the tangential blast ofthe forwardly-sloped blades such as I employ represent largely kinetic energy serving no real useful purpose in prior driers and therefore needlessly consuming power in its creation. The forwardly-curved blades employed in my drier mentum and which are thus quickly dried, comprise a much higher percentage of the total quantity of stock on the apron.

In furtherance of economy and efficiency of operation, the heated air used for drying is .asv hitherto recirculated repeatedly, through` the, stock, but in such manner that the only positive pressure existing within the. drier proper is iny` CII the drying chamber above the top run of the` v apron on which rests the stock. All the 'rest of 't the circuit of the air is effectediunder'negative pressure, suction. This is of considerable practical' value, because thus the unavoidable leaks inthe walls of the housing result in inflow of air at room temperature to act as part of the make-up air supply, rather than in escape of hot air with resultant loss of heat representing waste of fuel. Also,'at all points of its contact with the outside walls of the housing the yrecirculating air is thus sucked past such walls, thus avoiding the substantial transfer of its heat to'such walls which results from impact thereaga-inst of a blast under positive pressure. With average quality of insulation ther outside of the improved drier stays comparatively cool all over, although the temperatures employed within are well above those used heretofore 'in similar driers. In practice, driers embodying the features of the invention commonly attain a ratev of production 50% to 75% -greater than comparable prior apron driers of the same size.

By way of yfurther improving the uniformity of drying of the massof loose stock, the air is returned to ther blowers for Arecirculation by means of passages located at both lateral edges v of the apron, so that-the air passing througherating with the kinetic energy of the discharged" air to get the -air through the ystock remains more nearly constant across the widthof the apron at the underside of the top run, than in the prior one-sided arrangement. Other objects of the invention, and the man ner of their attainment, are as set forth hereinafter. v

An illustrative embodiment of the invention in a preferred form is shown in the accompany-` ing drawings, in which- Fig. 1 is a side elevation of the improved drier, showing also a hopper feeder for feeding the loose stock onto the apron. l

Fig.' 2 is a plan view of the same.

Fig. 3 is a vertical section on .line 3-3 of Fig. 1.

The housing of the drier is of usual construction, comprisingA a framework of structural. steel membersl `3, of various cross-sectionaziok tight.

the outside of which are applied the usual metalcovered panels 5 of heat-insulating material to form with the Hoor of the building a more or less air-tight enclosure. Through this housing travels a horizontally disposed apron 1 made up of perforated plates 9 carried by a chain IIJ having rollers II traveling on tracks I3 mounted on uprights 5 setin somev distance from the side walls of the housing At the discharge end of the housing |'is provided a smaller compartment or chamber I1, closed at top, rear, and

Vboth sides, and at the bottom by the floor of the room, which serves in conjunction with fixed bailes 2|, -23, 25, and exible baffle 21, together I, with' its own'flexible baille 29, to create a deadair space forming 'an air lock through which apron 1 and the stock borne on the top run `thereof may .emerge from the drying chamber 3| without the loss of a great amount of the heated air contained in such chamber under positive pressure, and without being blown `out of the drier. A similar air-lock I9 at the feed end of the machine performs a like service, in conjunction with fixed baffles 33, 35, 31, and ilexble ybaille 39 in the front end of housing the top of compartment I9 being open to admit the stock fed thereinto by the hopper feeder. Doors 38, 4U give the operator access to the drierv interior. Sprockets 4I for the feed end of apron 1l are carried on shaft 42 mounted in air-lock I 9 by'means of bearings 43 receiving its journals, these bea-rings being adjustable lengthwise ofthe housing :between their supporting guides 45 by means of a screw 41, to keep the apron Suitable bearings for the shaft 5I carryingsprockets 49 around which the delivery endof the apron reverses its direction of travel arepprovided in connection with the side walls of air-lock |1.` The apronis driven through a sprocket appliedto the shaft 5|, such sprocket being driven througha variable speed unit 53 of standardconstruction propelled by motor 55.

, The hopper feeder is of customary construction, comprising'a hopper 51, a vslatted apron 59 forming its bottom, a spiked apron 6| to elevate the stock, and a cleated cylinder or doffer 63 dumping the stock lifted by the spiked apron into the throat dened `byinclined baille 65 and the two side walls 'of compartment I9, there to be deposited on the top run of apron 1.

f The kdrying chamber vis defined by a horizontal baille. 61 extending for the full length of housing and widthwise between uprights I5, as well as by two vertical baiiles 69 applied to the uprights and of equal length with baille 61. v'Io prevent escape ofthe stock from the lateral margins of the apron 1, the usual guards 1| are provided on the ends of each-plate 9, for engagement with packing material applied along the bottom edges of vresilient bailles 13 fixed to the lower edges of bailles 69 and coextensive` therewith. Bailes'Zl and 33, with their exible baflles 21 and 39 depending respectievly therefrom, 'close the ends of this chamber, so that when air is blown into the chamber its onlyrway out is through the apron and the stock lyingthereon, with the exception of small 'un'- avoidable'leakage elsewhere.

lMultivan@ centrifugal blowers 15 which blow air into the drying Vchamber are locatedV in the top of the housing immediately above the baille G1 andwith their discharge ports extending through apertures made'therefor in such baille and pointed squarely =atlthe apron below," The blowers are mounted: -threeor moreto'aishaft 16 across the' housing.' As they must be spaced apart alon'gltheshaft in order to admit air to the axial intake ports in the sides of their involute housings, the blowers of the successive shafts disposed at intervals along the length of the apron are staggered with respect to the blowers of the preceding shaft, so as to cover the zones of stock which lay out of the path of the blasts of the immediately preceding blowers; thus the entire surface of the apron is uniformly covered by the blasts in the course of its travel. To avoid subjecting the bearings 1l of these blower shafts to the heat within the housing, they are located in air-wells 'I9 opening to the air outside the housing. Spaces are left in the housing around these shafts, through which air is sucked in, cooling the bearings and also supplying fresh air` to the interior.

The shaft 'it of each row of blowers is driven by its individual motor ill by V-belts 83 and pulleys.

As indicated in the right-hand blower of Fig. l, the blades of the rotor 85 are slanted or curved sharply forward to impart kinetic energy to the blast, as well as building up static pressure.

The air passing through the apron l and the stock thereon returns to the blowers by passing transversely of the apron through the space between its upper and lower runs, around both lateral margins of the upper run, and up through the space between these margins and the sidewalls of the housing, all as indicated by the arrows in Fig. 3. Across this latter space at each edge of the apron are located extended-surface heaters 8l, fed by pipes 89 from a suitable source of steam, so that all recirculated air entering the blowers is forced to pass through such heaters and to be raised to the desired temperature.

The major part of the resistance to the recirculation of the air is met with in passing through the stock 8 on the apron. Thus, the air forced into the drying chamber 3| is raised above atmospheric pressure and driven through the stock by its combined momentum and static pressure, but as soon as it has passed through it is subjected to the exhausting action, suction, of the blower intakes and is reduced to a sub-atmospheric or negative pressure. Hence the air is at no place forced against any outer wall of the drier under positive pressure, but wherever it contacts such wall it is under a negative pressure, or induced draft; under these circumstances it imparts much less of its heat to the outer walls. Also, all leaks through the outer walls are inward.

This favorable situation is enhanced by the location of the intake of an exhaust duct 9| in the space between one edge of the top run of apron 'l and the adjacent outer wall of the housing, (Fig. l). This duct, split to straddle one of the air-wells l for the blower-shaft bearings, is connected at its top end with the intake of an exhaust blower 83 driven by its motor 95, and serves as usual to carry off moist air. Make-up air is provided through leaks, by air wells 19, and underneath the apron at the flapper bales 2l, 29, 39. The heater 81 of this section is omitted to make room for the duct.

Horizontally disposed screens 91, coextensive with the apron in width, are slidably mounted in guides 99 beneath the top run of the apron, to

stop lint which passes through the apron' from entering and collecting in the heaters. They are withdrawn by first removing panels |33 equipped with handles It l and come out horizontally without spilling their burden of lint.

With the blowers located in the top of the housing, free access is aorded to the entire space within the drier below the top run of the apron, for cleaning, and for adjustment and repair of the apron. Removal of the lower and middle side panels 5 is easily effected for this purpose, and the heaters 8l are then easily accessible for cleaning, and the floor below the apron can be swept clean.

What I claim as my invention is:

i. A drier having in combination a housing, means transporting the material to be dried through the housing in a horizontal sheet, a plurality of Shafts extending across and supported above said transporting means at spaced intervals in the length thereof, a plurality of blowers in spaced relation on each shaft, and staggered with relation to the blowers on an adjacent shaft, blowing against the surface of the sheet and uni# formly covering the entire width thereof with their blasts, means rotating the shafts, and means leading air passing through the sheet around both lateral edges of the sheet back to the blower intakes.

2. A drier having in combination a traveling apron, a housing through the end-walls of which the apron travels to traverse the interior of the housing, means creating an air-pressure greater than atmospheric within the housing over the surface of the apron, means guiding the air thus driven through the apron around the edges thereof back to the pressure-creating means for recirculation, entrance and exit ports in the housing for the apron to pass through, an antechamber enclosing all of the feed end of the apron outside of the housing and closed on all sides save at the top where it is open for the introduction of the material to be dried, and a chamber adjacent the end-wall of the housing enclosing all of the discharge end of the apron outside the housing except the reverse bend thereof and closed on all sides to create a dead-air chamber, these two chambers serving as air-locks to prevent the material from being blown out of the drier.

3. A drier having in combination a housing, means transporting the material to be dried through the housing in a horizontal sheet, a plurality of shafts extending across and supported above said transporting means at spaced intervals in the length thereof, a plurality of blowers in spaced relation on each shaft, and staggered with relation to the blowers on an adj acent shaft, blowing straight down against the surface of the sheet and uniformly covering the entire width thereof with blasts penetrating the material to be dried by reason of the momentum of such blasts, means rotating the shafts, and means leading air passing through the sheet around both lateral edges of the sheet back to the blower intakes.

FRANK B. MORRILL. 

